/*
 * Winny P2P Application Detection
 * 
 * Copyright (C) 2006 Sourcefire, Inc. All Rights Reserved
 * 
 * Writen by Lurene Grenier <lurene.grenier> & Brian Caswell <bmc@sourcefire.com>
 *
 * This file may contain proprietary rules that were created, tested and
 * certified by Sourcefire, Inc. (the "VRT Certified Rules") as well as
 * rules that were created by Sourcefire and other third parties and
 * distributed under the GNU General Public License (the "GPL Rules").  The
 * VRT Certified Rules contained in this file are the property of
 * Sourcefire, Inc. Copyright 2005 Sourcefire, Inc. All Rights Reserved.
 * The GPL Rules created by Sourcefire, Inc. are the property of
 * Sourcefire, Inc. Copyright 2002-2005 Sourcefire, Inc. All Rights
 * Reserved.  All other GPL Rules are owned and copyrighted by their
 * respective owners (please see www.snort.org/contributors for a list of
 * owners and their respective copyrights).  In order to determine what
 * rules are VRT Certified Rules or GPL Rules, please refer to the VRT
 * Certified Rules License Agreement.
 */

#include <string.h>

#include "sf_snort_plugin_api.h"
#include "sf_snort_packet.h"

int ruleWINNYeval(void *p);

/* references for sid WINNY */
/* reference:url,technet.microsoft.com/en-us/security/bulletin/ms06-007"; */
static RuleReference ruleWINNYref1 =
{
    "url", /* type */
    "en.wikipedia.org/wiki/Winny" /* value XXX - update me */
};

static RuleReference *ruleWINNYrefs[] =
{
    &ruleWINNYref1,
    NULL
};

static RuleOption *ruleWINNYoptions[] =
{
    NULL
};


/* metadata for sid 7019 */
/* metadata:service http, policy security-ips drop; */
//static RuleMetaData rule7019policy1 =
//{
//        "policy security-ips drop"
//};


static RuleMetaData *rule7019metadata[] =
{   
//    &rule7019policy1,
    NULL
};

Rule ruleWINNY = {
   /* rule header, akin to => tcp any any -> any any               */
   {
       IPPROTO_TCP, /* proto */
       "any", /* SRCIP     */
       "any", /* SRCPORT   */
       0, /* DIRECTION */
       "any", /* DSTIP     */
       "any", /* DSTPORT   */
   },
   /* metadata */
   {
       3,  /* genid (HARDCODED!!!) */
       7019, /* sigid da1421ff-dcf4-46af-bed7-154cc8a1fca5 */
       7, /* revision 838f8744-d660-49fa-aa17-0c637faf7996 */

       "policy-violation", /* classification, generic */
       0,  /* hardcoded priority XXX NOT PROVIDED BY GRAMMAR YET! */
       "PUA-P2P WinNY connection attempt",     /* message */
       ruleWINNYrefs /* ptr to references */
       ,rule7019metadata
   },
   ruleWINNYoptions, /* ptr to rule options */
   &ruleWINNYeval, /* ptr to rule detection function */
   0, /* am I initialized yet? */
   0, /* number of options */
   0  /* don't alert */
};

#define WINNYSWAP(x,y) tmp = x; x = y; y = tmp;

/* detection functions */
int ruleWINNYeval(void *p) {
    uint32_t i;
    const uint8_t *ptr, *beg_of_payload, *end_of_payload;    
    uint8_t t, tmp;    
    unsigned char outdata[5];
    uint8_t s[256] = {
	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
	0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
	0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
	0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
	0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f,
	0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,
	0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
	0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f,
	0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
	0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,
	0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
	0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,
	0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,
	0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
	0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,
	0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff
    };
    SFSnortPacket *sp = (SFSnortPacket *) p;

    if (NULL == sp)
        return RULE_NOMATCH;

    if (NULL == sp->payload)
        return RULE_NOMATCH;

    if(getBuffer(sp, CONTENT_BUF_NORMALIZED, &beg_of_payload, &end_of_payload) <= 0)
        return RULE_NOMATCH;

    if (11 != (end_of_payload - beg_of_payload))
        return RULE_NOMATCH;

    ptr = beg_of_payload+2; t = 0;
    for(i = 0; i < 256; i++) {
        t += s[i] + ptr[i % 4];
        WINNYSWAP(s[i], s[t])
    }
    ptr = beg_of_payload + 6; t = 0;
    for (i = 1; i < 6; i++) {
        t += s[i];
        WINNYSWAP(s[i], s[t])
        outdata[i-1] = ptr[i-1] ^ s[((s[i] + s[t]) % 256)];
    }
    if (!memcmp("\x01\x00\x00\x00\x61", outdata, 5)) {
        return RULE_MATCH;
    }
    return RULE_NOMATCH;
}
